12 bolt 4 series carrier question

[SS69chevelle]

Hello all, Does anyone know specifically what to look for on the 4 series carrier to determine if it is a COPO carrier vs the standard one? The carrier has black marker writing that says "r/b Moroso" which I assume means rebuilt by Moroso. The gears are 17-10 and new, the clutches are new and the unit does not look like it was run after the suspected rebuild. The carrier is dated C 13 J (Mar 13th 1969). With the parts is a box of 12 bolt posi carrier gears that are 16-10 and identified as COPO gears, do not know if they came from this carrier or not. Any help would be appreciated to determine if the carrier is a COPO unit or not. Thanks Andy

Attached a few pics for reference.